Metacosma Kuznetzov, 1985

Type species: Metacosma impolitana Kuznetzov, 1985, by original designation and monotypy.

Redesciption (excluding M. miratorana). Head: Antenna (Figs. 2, 3) in male with a notch near base. Labial palpus (Fig. 3) with second segment expanded distally by scales, roughly triangular, ascending; third segment short, porrect. Thorax: Forewing (Figs. 1, 7) long and narrow, without costal fold in male; M-stem and chorda absent; all veins present and separate beyond discal cell; R 3 approximated to R 4 at base. Hindwing (Figs. 1, 7–9) almost equal to forewing in width, with sparse cubital pecten. Hindwing in male with anal margin produced into a free elongate lobe with the outer edge folded upward and embracing a scale pencil from the base of the anal area (Figs. 1, 7, 8); M 2 and M 3 nearly approximated at base and from lower angle of discal cell, CuA 1 from lower margin of discal cell near angle. Abdomen: Hindmargin of S8 strongly bilobed in male (Fig. 11). Male genitalia (Fig. 10) with valva without basal process; cucullus with a bristled flap produced from dorsal margin near its apex, with one or two strong spines on the apex and three to six similar ones along the ventrodistal margin. Uncus a short process, often distally bifid. Socii elongate lobes with long setae, completely fused with diaphragma. Female genitalia (Figs. 12, 13) with S7 heavily sclerotized, wide, divided into three areas: raised, semicircular median plate and variously shaped lateral plates. Sterigma funnel-shaped, fused with folded posterior apex of S7 (ostium bursae behind S7) (Fig. 13: arrow). Ductus bursae with long, anteriorly bifurcate sclerotization in anterior 3/4. Corpus bursae ovate or rounded, spinulose except around signum, with two, rather small horn-shaped signa.

Remarks. Metacosma is characterized by the male hindwing with a free elongate fold embracing a scale pencil from the base of the anal area (Figs. 1, 7, 8); the cucullus with a bristled flap produced from dorsal margin near the apex and with one or two strong spines on the apex and three to six similar ones along the ventrodistal margin (Fig. 10); and the seventh sternite of the female consisting of raised, semicircular median plate and variously shaped lateral plates (Figs. 12, 13). All these character states appear to represent synapomorphies for members of the genus.

The genus belongs to the Spilonota group, an informal genus group proposed by Horak (2006), comprising Eccoptocera Walsingham, Hendecasticha Meyrick, Hermenias Meyrick, Holocola Meyrick, Lepidunca Diakonoff, Parienia Berg, Protithona Meyrick, Spilonota Stephens, Strepsicrates Meyrick, and Xenosocia Diakonoff. Metacosma shares with members of the Spilonota group the following derived traits presented by Horak (2006): antennal notch in male, extended anal region in male hindwing with upturned anal margin folded over long scale pencil from base, funnel-shaped sterigma fused with S7, and a tendency for signa to be reduced or lost and bursa to become strongly spinulose.

In addition to the above genera the North African Cirrilaspeyresia Razowski (type species: Euxanthis imbecillana Kennel) may belong to the Spilonota group and may be most closely allied to Metacosma. Cirrilaspeyresia imbecillana (Kennel) shares with the Spilonota group the tendency towards reduction of the signa (absent in C. imbecillana) and the funnel-shaped sterigma fused with S7 (Razowski 1961: fig. 25), but in the drawing of the adult head the antenna has no notch at its base (Razowski, 1961: 675, fig. 3), though there is no indication of its sex. Moreover, this species is similar to members of Metacosma in having the cucullus with strong spines along the outer and ventral margins (Razowski 1961: fig. 11).

Prior to this report, five Metacosma species were known mainly from North East Asia (see the checklist below). However, the generic assignment of M. miratorana Kuznetzov is questionable, as no synapomorphies have been identified that would support this assignment, though the species is known only from males. Furthermore, M. miratorana differs from the other species of Metacosma in possessing semioval socii and long basal processes (Kuznetzov 1988: 629, fig. 21). Superficially it is reminiscent of some species of Gypsonoma Meyrick (see also Nedoshivina 2010: 343, pl. 9, fig. 67).